In the saddle-back tamarin, a South American primate, chemical signals deposited by marking with specialized scent glands are important in aggressive behavior and in the establishment of social dominance. Dominance, in turn, is a prerequisite for female reproductive success, since the Alpha-female suppresses cyclicity in all submissive females. Pilot studies suggest that this suppression is partially mediated by the scent marks of the Alpha-female. The proposed experiments, using behavioral and endocrinological methods, will investigate the extent to which gonadal and adrenal hormones determine the ontogenetic development of scent glands, signalling (marking) behavior and aggression and the degree to which these parameters are hormone independent. Some of the endocrine events in young animals maturing under controlled social conditions will be studied to provide data on which future experimentation on possible pheromonal influences on the timing of puberty can be based. In addition, the hormone-scent gland interactions will be studied in vitro by cell and tissue culture methodology in order to avoid utilizing a large number of valuable primates. At present, most of our knowledge about hormonal influences on social behavior are derived from research on rodents. The proposed studies will increase the still scant body of knowledge in primates and ultimately will lend to a better understanding of the interactions between hormones and behavior in man.